Welder transformer



. Aug-.4, 1970 w. P. JosT TAL I3,523,272

WELDER TRANSFORMER Filed July 24, 1968 3 Sheets-Sheet l T e e N .NW1 NNM1 df/# ,M V O., uw... n O M4. M -im ,WWMTH 111111 -mi TW O a. fh@ O Ow @no /A bw/k N Wu N\ L hmmm u NN AWN E J w@ MW km. m, www g vv ./\Mw`@MJ L mju. O Non V. v. NN mms. m\ \m1 Sm, mv@ @v /l w Il!" H I [Il m,\NIH 1 HQ@ ou |1|| I Y MY C O DN .wNwmllJJ @w l(\ Jml I WN\ ,f\Q\ #1h QQQQ\ Aug. 4,'1970 w. P. .JosT ETAL v WELDER TRANSFORMER 3 Sheets-Sheet EFiled July 24, 1968 Aug. 4, 1970 w. P. Jos'T ETAL WELDER TRANSFORMER lFiled Jluly 24, 1968 www 3 Sheets-Sheet 3 W04 752 P JOS 7' dof/M A),R4L/wee iatale/mcy United States Patent O 3,523,272 WELDER TRANSFORMERWalter P. Jost, Webster, and John A. Palmer, University City, Mo.,assiguors to Emerson Electric Co., St. Louis, Mo., a corporation ofMissouri Filed July 24, 1968, Ser. No. 747,373 Int. Cl. H01f 21/06 U.S.Cl. 336-133 7 Claims ABSTRACT OF THE DISCLOSURE A core-type transformerfor an AC arc Welder in which the primary and secondary windings arealuminum strips interleaved with woven glass tape as the dielectric. Thewoven glass tape acts almost exclusively as a mere spacer. A second coreis movable into and out of the window of the Wound core. The second coreis mounted on a vertical shaft journaled in a pair of brackets onhorizontal reaches of the Wound core. The vertical shaft is held inV-shaped seats in the 'brackets by relatively stiff keeper platesbearing against the opposite side of the shaft. The shaft extendsthrough a sheet metal top cover and is capped by a pointer and handlefor rotating the shaft and second core. Pin keys in the shaft above andbelow the top cover hold flanged locks. A cam on the handle compressesthe top cover between the locks when the handle is pivoted downwardly. Atable on the top cover indicates the output amperage of the transformeras the pointer moves and includes a set of colored bands, the colors ofwhich correspond to American Welding Society code colors of some weldingelectrodes to be used with the Welder.

BACKGROUND OF THE INVENTION This invention relates to transformers forAC are Welders. It has particular, but not exclusive, application to acore-type transformer having a second core movable into and out of thewindow of the wound core.

Transformers for so-called limited service arc Welders provide avariable low voltage high amperage AC output. One method of providing astepless variation in amperage over a relatively extended range is toutilize a core-type transformer having primary coils and one set ofSecondary coils wound on one vertical leg of the frame and a second setof secondary coils, or reactors, wound on the other vertical leg of theframe. The individual coils of each set of coils are electricallyconnected in series, and the rst set of secondary coils is electricallyconnected in series to the `reactors. A low amperage outlet plug may beelectrically connected to the first set of secondary coils through thereactor coils and a high amperage outlet plug may be electricallyconnected to the first set of secondary coils through a single reactorcoil. If more than two reactor coils are provided, other plugs may alsobe provided. A stepless range of amperage output is provided at eachplug by a second core which is movable into and out of the window of thewound frame. The movable core may be simply a laminated block nearly theheight of the window and may be mounted on a vertical shaft for rotationinto and out of the window. As the movable core is moved into the windowof the wound core it acts as a magnetic shunt, which decreases theoutput of the reactor coils.

Certain problems inhere in a transformer of this design. A particularlycompact and efficient coil design is required. Furthermore, therotational and vibrational strains which are physically and magneticallyexerted on the movable core require particularly rattle-free andwear-resistant bearings for the movable core shaft, an easy means formoving the core into and out of the wound frame window and a convenientyet effective method for locking the shaft at any desired position.Finally, the stepless control requires a convenient method of indicatingthe output amperage at any position of the movable core and a method ofcorrelating this information with the choice of an appropriate electrodefor any given job within the capabilities of the transformer.

One of the objects of this invention is to provide a welding transformerwhich meets the foregoing requirements better than presently knownwelding transformers.

Other objects will occur to those skilled in the'art in the light of thefollowing description and accompanying drawing.

SUMMARY OF THE INVENTION In accordance with this invention, generallystated, a

variable welding transformer is provided having primary coils andsecondary coils, each of which includes a coiled flat strip ofelectrically conductive material, successive reaches of which areseparated by a woven glass tape. The weave of the glass tape isrelatively loose, and therefore the coils are effectively provided withan air dielectric.

The primary coils and at least some of the secondary coils arepositioned on parallel legs of a stationary core, or frame. A second,movable, core is mounted on a shaft, which in turn is rotatably mountedon the frame by a novel support bracket. The support bracket includes ahorizontal plate secured to a horizontal reach of the frame. An apertureis provided in the horizontal plate. A V-shaped seat at one margin ofthe aperture receives a curved surface of the shaft, and a generallyvertical keeper plate biases the shaft into engagement with the seat. Inthe preferred embodiment, two support brackets are provided, one on eachhorizontal reach of the frame, and the shaft is journaled to restrictits vertical motion.

Novel means are also provided for rotating the shaft and movable core,locking the shaft at a desired position, and indicating an appropriateposition of the movable core for welding operations utilizing particularoutput terminals and electrodes and for particular work applications.

The rotating and locking means are attached to a section of the shaftextending through a top cover on the Welder, and include a cam pivotallymounted on the shaft and a handle secured to the cam. The cam is movablefrom a release position to a lock position, in which the cam holds theupper cover tightly against a lower bearing surface on the shaft belowthe upper cover.

In the preferred embodiment the lower bearing surface includes a closurepiece which rests on an abutment on the shaft. An upper closure piece isalso provided, between the cam and the upper cover. Each closure piecehas a larger outer diameter than the aperture in the upper cover and isprovided with an aperture through which the shaft extends, so that thecam compresses the upper cover between the upper and lower closurepieces. Also in the preferred embodiment the upper closure piece is acupped lock, the lip of which rests on the upper cover, and the lock andcam are both connected to the shaft by a pivot pin extending through theshaft above the upper cover.

The indicating means include a pointer mounted on the upper end of theshaft for rotation therewith and a number of colored bands on the uppercover, the color of each band corresponding to a code color of a weldingrod'. In the preferred embodiments, each colored band is divided intosegments, and each segment represents a recommended electrode size foruse at the amperage of one of the output terminals.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, FIG. 1 is a view infront elevation, partially cut away, of a Welder transformer of thisinvention;

FIG. 2 is a view in side elevation, partially cut away, of the Weldertransformer shown in FIG. 1;

FIG. 3 is a top plan View of the Welder transformer shown in FIGS. 1 and2;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. l;

FIG. =6 is a sectional view also taken along the line 5-5 of FIG. 1,partially cut away;

FIG. 7 is view in side elevation, partly in section, of the rotating andlocking means of the Welder shown in FIGS. 1-6, with a pointer housingremoved;

FIG. 8 is a View in side elevation of the pointer housing; and

FIG. 9 is a circuit diagram of the Welder transformer shown in FIGS.l-8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,reference numeral 1 indicates one illustrative embodiment of Weldertransformer of this invention. 'Ihe transformer 1 includes a housing 2,a wound core 3, a movable core assembly 6, a rotating and lockingmechanism 8 and an indicating means 10.

The housing 2 includes a pair of base brackets 20, a guard screen 21welded to the base brackets 20, a pair of sheet metal side panels 22, asheet metal piece 23 which is bent to form a front panel 24 and asloping top panel 25, and a rear panel 26. The side panels 22 arescrewed to the base brackets 20` and to wings on the sheet metal piece23.

Mounted on the inner face of the front panel 24 and extending through itare an on/off switch 9, a ground cable 11, a high outlet plug 12 and alow outlet plug 13. The outlet plugs 12 and 13 are alternativereceptacles for a welding electrode cable. Mounted on the back panel 26are a fan 14 which draws air through the housing and an outlet box 15for a power cord 16.

The wound core 3 includes a rectangular core or frame 30 welded to thebase brackets 20 through the guard screen 21. The frame 30 may be madeof ordinary L- laminations. The upper and lower horizontal reaches ofthe frame 30 are provided front and back with stiifener laminations 31,and the frame and stitfeners are held together by through bolts at thecorners of the frame 30.

Mounted on one of the vertical legs of the frame 30 are a set of fourprimary coils 32 and a set of two secondary coils 33, positioned betweenthe primary coils 32 and the frame 30. The secondary coils 33 are spacedfrom the vertical leg of the frame 36 by four corner spacers 34. Theprimary coils 32 are spaced from the secondary coils 33 by spacer blocks35 around the outboard side of the coils and by a strip of insulation 36at the inboard side of the coils.

Two further secondary coils or reactors 37 and 38 are mounted on theother vertical leg of the frame 30. The reactors 37 and 38 are spacedfrom the Vertical leg by four spacers 39, which are essentially the sameas the spacers 34 on the other leg. t

Each of the coils is formed of a continuous strip of bare aluminum 40`interleaved with woven glass tape 41 having a slightly greater widththan the aluminum strip. The inner (start) end of the top primary coil,the outer (finish) end of the aluminum strip of the bottom primary coil,and both the start and iinish ends of the intermediate coils are formedinto leads by bending the aluminum strip at on itself and taping thefold flat against the coil with pressure sensitive polyester tape. Asuitable tape for this purpose is sold by Minnesota Mining &Manufacturing Company as #55 Scotch polyester pressure sensitive tape.All of the other leads are formed by cold welding a copper strip leadtransverse of the aluminum strip, near its end. Scotch #55 tape is alsoused to hold these ends and leads flat. The primary coils 32 and thereactor coils 37 and 38 are wrapped with a length 42 of Scotch #69 tape,around their outer faces.

The leads are connected as follows. The start lead 45 of the bottomprimary coil and the yfinish lead 46 of the top primary coil areelectrically connected to the on/olf switch 9, and the other primarystart leads 43 are each cold welded to the primary nish lead 44 of thecoil below. The start lead of the lower secondary coil 33 is cold weldedto the nish lead of the upper secondary coil 33, the finish lead 47 ofthe lower secondary coil is connected to the ground cable 11, and thestart lead 48 of the upper secondary coil 33 is electrically connectedto the iinish lead 49 of the lower reactor coil 37. The start lead 50 ofthe lower reactor 37 and the finish lead 51 of the upper reactor 38 areboth connected to the high output plug 12. The start lead of the upperreactor 38 is electrically connected to the low output plug 13.

It wil be seen that the primary coils 32 and the first set of secondarycoils 33 are each connected in series and that the secondary coils 33are coupled to the output plugs 12 and 13, respectively, through thelower reactor coil 37 and through both reactor coils 37 and 38 inseries.

The fan 14 is electrically connected to the same terminals of the on/offswitch 9 as the primary leads 45 and 46, and the power cord 16 iselectrically connected to the other side of the switch 9, so that thefan and primary coils are both activated when the cord 16 is pluggedinto a source of single phase 230 volt alternating current and theswitch 9 is turned on.

Merely by way of illustration, the coils may be made of the followingmaterials and may have the following dimensions:

Primary coils 32 (each 39 turns of .008 X 11A@ inch bare aluminuminterleaved with .004 x 11A inch woven glass tape (e.g. Hess & GoldsmithA-weave). Secondary coils 33 9 turns (upper coil) and 81/2 turns (lowercoil) of .011 X 2% inch bare aluminum interleaved -with .004 x 21/2 inchwoven glass tape. Reactor coil 37 (lower) 191/2 turns .018 X 11/16 inchbare aluminum interleaved with .004 x 2 inch woven glass tape. Reactorcoil 38 (upper) 22 turns .011 x 1?/16 inch bare aluminum interleavedwith .004 x 11/2 inch woven glass tape.

The wound core 3 described provides a class H transformer having amaximum operating temperature of The movable core assembly 6 includes avertical round shaft 60, the lower end of which extends through theguard screen 21 and the upper end of which extends through the uppercover 25. The shaft 60 is rotatably mounted adjacent the forward face ofthe core 30 by an upper bracket 61 and a lower bracket -62 on the core30. The shaft 60 is reduced in the area of each bracket. Each of thebrackets 61 and 62 includes a horizontal bracket plate 63 Welded to theoutboard face of a horizontal reach of frame 30- and extending forwardof the frame 30. The lower bracket plate L63 is welded through the guardscreen 21. A slot 64 eX- tends rearward from the forward edge of eachplate 63. The rearward end of the slot 64 forms a V-shaped seat 65 toreceive a journaled reduced section 66 of the staft 60. The solt 64 iswider than the journaled section 66 of the shaft 60, so that thejournaled section 66 makes two point contact with the seat 65. The lowerjournaled section 66 has a height equal to the thickness of the plate63, to prevent vertical movement of the shaft 60, and the upperjournaled section 66 has a height somewhat greater than the thickness ofthe plate 63 to prevent the precise distance between the plates 62 frombecoming critical for smooth rotation of the shaft 60. A bent keeperpiece `67 is held to the plate -63 by bolts 68. The keeper piece 67 isformed like a leaf spring so that a relatively small bearing surfacenear its free end exerts a strong rearward pressure on the shaft 60 whenthe bolts 68 are drawn tight.

Welded to the shaft 60 between the support brackets 61 and 62 is amovable core 70. The movable core 70 is a stack of rectangularlaminations with a pair of stiffener pieces at the top and bottom of thestack. It is welded together along its sides. The movable core 70 is soproportioned and positioned on the shaft 60 that when it is swung intothe window of the frame 30 it is substantially the same depth as theframe 30, its laminations run in the same direction as those of theframe 30, and its upper and lower edges miss the inboard edges of theupper and lower horizontal frame members by about one sixteenth of aninch. A stop bracket 71 is Welded to the movable core 70. An upper edgeof the stop bracket 71 extends above the movable core 70 and abuts thestilfener 31 when the movable core 70 has been swung completely into thewindow of the frame 30. A perpendicular upper edge of the stop bracket71 abuts the stitfener 31 when the movable core 70 has been swungcompletely out of the window, as shown in broken lines in FIG. 6.

The shaft 60 is made of a nonmagnetic material such as nonmagneticstainless steel. Because the movable core assembly 6 therefore isaffected by the magnetic flux of the frame 30 only through the movablecore 70 and the shaft -60 is restrained from vertical or horizontalmovement by metal-to-metal contact with the brackets 61 and `6-2, themovable core assembly 6 is free of vibration in use.

The rotating and locking mechanism 8 is attached to the upper end of theshaft 16, which extends through an aperture 81 in the top cover 25. Anarcuate perforation in the top cover 25, outboard of the aperture 81,allows a horizontal shelf 82 to be formed in the sloping top cover 25. Apair of closure pieces in the form of flanged locks 83 and 84 arepositioned on the shaft 60 respectively above and below the shelf 82 andare respectively keyed on the shaft in proximity with the shelf 82 bykeeper pins v85 and 8-6 through the shaft.

Each of the locks 83 and 84 includes a hollow stem 87 and a hollow cup88. The pins 85 and 86 lie in notches 89 in the stems 87 of the locks 83and 84 and cause the locks 83 and 84 to rotate with the shaft 60.Although the lips of the lock cups 88 preferably touch the shelf 82,they are not held tightly against it by the pins and 86, and the locks83 and 84 by themselves do not restrict the free rotation of the shaft60.

A stop 90, having a hollow stem and an enlarged cap 91, is held by a capscrew 95 to the upper end of the shaft `60. A U-shaped cam 92 is alsotrapped on the shaft 60, between the cap 91 of the stop 90 and the cup88 of the upper iiange lock 83, by the pin 85 which extends throughelongate slots 93 in the parallel legs of the cam 92. A handle 94 isscrewed to the cross-piece of the cam 92. When the handle 94 is in agenerally horizontal position, as shown in FIG. 4, the slot 93 is angledapproximately 45 from the Vertical, and when the handle 94 is raised theslot 93 approaches the vertical. The surface of the cam in Contact withthe lock cup 88 is in the form of a smooth arc having a center ofcurvature below and to the handle side of the center of the slot 93. Theedge of the cam 92 which engages the stop cap 91 has a much shortercurved section between two straight sections to provide dente locked(handle down) and unlocked (handle up) positions. The height of the cam,between the stop and the cup 88 of the upper lock 83 is greater, ofcourse, in the locked position than in the unlocked position.Furthermore, the shapes of the upper and lower edges of the cam 92 aresuch that there is little change in this height near the lockedposition, and the slot 93 allows suiiicient downward motion of the cam92 relative to the pin 85 to make locking and unlocking relativelysmooth and eifortless. It will be seen that when the handle 94 israised, the locks 83 and 84 are not compressed and the shaft 60 andmovable core 70 may be swung by turning the handle 94. When the handle94 is pushed down t-he shelf 82 of the upper cover 25 is compressedbetween the lips of the cups 88 of the locks 83 and 84, and movement ofthe shaft and movable core is prevented. It will also be seen that theelongate slot 93 allows the cam 92 to be self-centering, frees it forsome vertical movement in the runlocked position, and allows adjustmentof the locking mechanism by adjusting the cap screw 95 above the stop90. Such adjustment may be desirable after the welder has been in longuse, to take up t-he play caused by Wear on the cam 92, stop cap 91 andupper lock cup 88. It nonetheless effectively traps the cam and holds itagainst lateral movement.

The indicating means 10 include a pointer 100 snapped over the top ofthe shaft 60 and a selector plate 101 secured to the upper face of thetop cover 25.

The pointer has a housing part 102 and a nger part 103, molded as asingle unit. The housing part 102 is pivotally mounted on the ends ofthe upper pin 85 on the shaft 60 by a pair of holes 104 in the sides ofthe housing part 102. The holes 104 are so placed that the pointer 100is spaced slightly above the selector plate 101 and can pivot around thepin 85. The housing section 102 is wider than the lock 83 and hides it.An aperture 105 is provided in the rear of the housing part v102 toaccommodate the handle 94. The forward upper edge 106 of the aperture105 is bent rearwardly downward to allow the handle 94 to be pulled upover the top of the housing section 102 of the pointer 100.

The ngcr part 103 includes a small foot 107 for holding the finger part-103 above the surface of the selector plate 101 and a seat 108 for aclear plastic lens 109.

The selector plate 101 extends below the forward edge of the top cover25 carries labeling for the output plugs 12 and 13. The output plugs 12and 13 are for simplicity marked A and B respectively. The portion ofthe selector plate 101 which lies beneath the sweep of the lens 109 onthe pointer 100 is provided with a table which includes a set of coloredbands 110. In this illustrative embodiment, thirteen bands are provided.The forward edge of each band is labeled either A or B to correspondwith the labeling of the high and low output plugs.

The outer band, labeled A, and the next band, labeled B, carry numbersat spaced intervals along their lengt-hs indicating the amperage outputof their respective output plugs at that particular position of thepointer 100. Thus, in this example, when the pointer is in itsforwardmost position (rotated counterclockwise) the number on the outerband under the plastic lens 109 is 180, which indicates that the outputfrom the A (high) output plug is 180 amps. This end of the second bandis marked 85 to indicate the amperage at the B (low) outlet plug. Itwill be seen that at this position of the pointer y100 the movable core70 is completely out of the window of the frame 30 and the stop bracket71 prevents further counterclockwise movement of the shaft 60. When thepointer 100 has been rotated clockwise to the rearward end of the bands,the indicated amperage on the A band is 85 and on the B band is 30. Atthis position of the pointer 100 the movable core 70 is rotatedcompletely into the window of the frame 30 and the shaft 60 isrestrained from further rotation by the stop bracket 71. The amperagebands thus indicate that a continuous range of amperages from 30 to 180is provided. The intermediate numbers on the outer two bands are chosento fall at generally even spacings on the bands and represent ranges offrom 25 amps to amps.

The remaining eleven bands are colored to represent the spot color orend color, or both, of commonly used welding electrodes. The rearward(clockwise) end of each band, or set of bands, is labeled with the codenumber of the electrode having the indicated code color and with thetype of material appropriately welded with this type electrode. Thebands are divided into segments, or ranges, each of which is marked witha number. The number indicates the diameter of a welding rod which isappropriate to that range. Since each range indicates a particularspread of amperages for a particular outlet plug, indicated by the labelat the forward end of that band, turning the pointer to that rangeautomatically provides the proper amperage at the indicated output plugfor the electrode chosen.

A user desiring to weld a particular kind of material simply looks atthe selector plate to deter-mine the code number or code colors of anappropriate type welding electrode, chooses an electrode of that type inan appropriate size lifts the handle 91 to rotate the pointer 100, setsthe position of the pointer 100 at a position somewhere in that diameterrange on the appropriate band, and pushes the handle 94 down to lock themovable core 70 in place. He then notes whether this band is labeled Aor B and plugs the electrode cable into the appropriate output plug. Hedoes not need to go to a separate source to discover a suggestedamperage range for that particular electrode and in fact does not needto know amperages at al1.

In this illustrative embodiment, the two bands immediately interior ofthe amperage bands indicate diameter ranges for E6011 electrodes, usedfor welding mild steel, from a diameter of 5%6 at the upper(counterclockwise) end of the outer A band to 5%4 at the lower(clockwise) end of the inner B band. Both of these bands are coloredblue to indicate the spot color of E6011 electrodes. The next two bands,also labeled A and B, indicate diameter ranges of H6013 electrodes, alsoused for mild steel. 'I'he bands cover the same ranges as the E6011bands and are colored brown to indicate the spot color of E6013electrodes. The next two bands, also labeled A and B, are for machinablecast iron electrodes for Welding cast iron. The A band is orange and theB band is blue to indicate the end color and spot color respectively ofthis electrode. The indicated ranges for these bands are from 3/16 to5%52. The next two bands, also labeled A and B, and colored brown andgreen respectively, are for hard surfacing electrodes having a brown endcolor and a green spot color. The next two bands, also labeled A and Bare for E7024 contact rods having a black end color and yellow spotcolor. The indicated ranges of these last four bands are discontinuousand cover only portions of the bands. The innermost band, colored red,is labeled A and indicates appropriate ranges for 1/s" and 3/16" cuttingrods having red end colors.

If the user wants to use an electrode not listed on the indicator plate101, he must consult a table of recommended amperages for that electrodeand set the pointer to an amperage on the outer bands in the recommendedrange. He then checks to see whether the band on which this amperageappears is the A lband or the B band, and plugs the electrode cable intothe appropriate output plug.

Numerous variations in the welding transformer of this invention, withinthe scope of the appended claims, will occur to those skilled in the artin light of the foregoing disclosure. For example, it is obvious thatone or both of the locks 83 and 84, or the adjacent faces of the uppercover, may be faced with a frictional material, or a washer offrictional material may be interposed between the locks and the uppercover. A suitable cork composition frictional material is sold byArmstrong Cork Company as NC 733 cork friction material. Therefore, ifsuch a frictional material is used and it rotates with the lock, it isincluded in the term closure pieceg if it does not, it is included inthe term upper cover. Either lock, or both, may be shaped differently,or omitted altogether. Diiferent indicator bands may be provided. Thesevariations are merely illustrative.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. In a variable welding transformer having a vertically alignedrotatable shaft and a movable core mounted on the shaft for rotationtherewith, the improvement cornprising a sheet metal upper cover, saidshaft extending through an aperture in said cover, a radially extendinglower bearing surface on said shaft below said aperture, said lowerbearing surface having a greater outer diameter than said aperture insaid upper cover, a `cam pivotally mounted on said shaft above saidupper cover, said cam being selectively movable from a release position,in which said shaft is rotatable through at least a predetermined arc,to a lock position, in which said cam holds said upper cover tightlyagainst said lower bearing su1face on said shaft.

2. The improvement of claim 1 wherein said lower bearing surfacecomprises a lower closure piece, and including an upper closure piecebetween said upper cover and said cam, said upper closure piece having agreater outer diameter than said aperture in said upper cover, each ofsaid closure pieces having an aperture through which said shaft extends;and an abutment on said shaft below said lower closure piece, said lowerclosure piece resting on said abutment, said cam bearing against saidupper closure piece when it is in its lock position for holding saidupper closure piece and said lower closure piece tightly against saidupper cover.

3. The improvement of claim 1 wherein said upper closure piece comprisesa cup, the lip of said cup resting on said upper cover.

4. The improvement of claim 2 wherein said upper closure piece and saidcam are both connected to said shaft for rotation therewith by a pivotpin extending through said shaft above said upper cover.

5. In a variable welding transformer having a movable core mounted on avertically aligned rotatable shaft the improvement `comprising a sheetmetal upper cover, said shaft extending through an aperture in saidcover; a pivot pin in said shaft above said cover; a cam, said camcomprising a yoke part having two parallel vertical sides and a handlepart, said parallel sides having a pair of elongate slots in themadapted to receive opposite ends of said pivot pin, said cam beingpivotable about said pivot pin from a lock position to a releaseposition.

6. In a variable welding transformer having a movable core mounted on avertically aligned rotatable shaft the improvement comprising a sheetmetal upper cover, said shaft extending through an aperture in saidcover; a pointer mounted on said shaft above said upper cover forrotation with said shaft, and a table on said upper cover, said tableincluding a plurality of colored bands, the color o'f each bandcorresponding to a code color of a welding rod.

7. In a variable welding transformer having a rectangular core having anupper and a lower horizontal reach.

and a movable core mounted on a vertically aligned rotatable shaft theimprovement comprising a pair of brackets mounted on said upper andlower horizontal reaches of said core, each of said brackets comprisinga horizontal plate, said plate having an aperture in it, said aperturecomprising a V-shaped seat, said seat being adapted to receive a curvedsurface of said shaft, and a keeper on said brackets, said keeper beingadapted to bias said curved surface of said shaft into engagement withsaid seat.

References Cited UNITED STATES PATENTS 2,490,629 12/1949 Jacobs 336-135XR 2,675,421 4/ 1954 Dexter 336-206 XR 2,998,583 8/ 1961 Worcester336-232 XR 3,394,332 7/ 1968 Peterson 336-130 THOMAS J. KOZMA, PrimaryExaminer U.S. Cl. X.R.

